#include 
#include 
#include 
using namespace std;
const int maxn = 1e5 + 10;
const int INF = 1e9;
vector > graph[maxn];
int n, m;
struct node {
    int idx;
    double cost;
    node () {}
    node(int _idx, double _cost) {
        idx = _idx;
        cost = _cost;
    }
    bool operator < (const node &tmp) const {
        return cost > tmp.cost;
    }
};

double prim() {
    priority_queue pq;
    pq.push(node(0, 0));
    vector dist(n, INF);
    vector visited(n, false);
    dist[0] = 0;
    double mst = 0;
    while(!pq.empty()) {
        node c = pq.top();
        pq.pop();
        
        if(visited[c.idx]) continue;
        visited[c.idx] = true;
        
        mst += c.cost;
        for(int i = 0; i < (int) graph[c.idx].size(); i++) {
            int neighbour = graph[c.idx][i].first;
            double weight = graph[c.idx][i].second;
            if(!visited[neighbour] and weight < dist[neighbour]) {
                pq.push(node(neighbour, weight));
                dist[neighbour] = weight;
            }
        }
    }
    return mst;
}
int main() {
    int t;
    cin >> t;
    
    while(t--) {
        cin >> n;
        vector > v;
        for(int i = 0; i < n; i++) {
            graph[i].clear();
            double a, b;
            cin >> a >> b;
            v.push_back(make_pair(a, b));
        }
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < n; j++) {
                if(i != j) {
                    double dist = sqrt((v[i].first - v[j].first) * (v[i].first - v[j].first) + (v[i].second - v[j].second) * (v[i].second - v[j].second));
                    graph[i].push_back(make_pair(j, dist));
                }
            }
        }
        printf("%.3lf\n", prim());

    }
    return 0;
}